JPH055642Y2 - - Google Patents

Description

[Detailed explanation of the idea]

<Industrial Application Field> This invention relates to a cylindrical alkaline battery. <Prior art> In a cylindrical alkaline battery, a cylindrical cathode can made of metal with a bottom is used. After a power generation element is housed in the cathode can, the opening of the cathode can is sealed with a terminal plate and an insulating gasket. A unit cell with this structure is used. The format of this unit cell is one in which a positive electrode can with a flat bottom is used, the power generation element is hermetically housed as described above, and then the positive terminal is welded to the bottom of the battery can, or the bottom is A type using a positive electrode can in which a positive electrode terminal is integrally formed by processing it into a convex shape in advance is known. Among these, the former type with a separate positive terminal is used especially for large-diameter batteries such as LR20, and is generally used after the positive terminal is brought into close contact with the bottom of the positive can. A structure is adopted in which the positive electrode terminal is fixed to the positive electrode can by spot welding or the like at the periphery. By the way, although this type of alkaline battery can easily draw a large current and has excellent discharging performance, it is possible that impurities such as heavy metals may be mixed into the battery or that problems may occur due to abnormal usage such as over-discharging or charging. There is a high risk that the battery will swell or explode due to an abnormal increase in the internal pressure of the battery due to a large amount of hydrogen gas. For this reason, current cylindrical alkaline batteries are equipped with an explosion-proof structure by providing a thin-walled part in the synthetic resin sealing gasket that is attached to the positive electrode can opening along with the negative electrode terminal plate. By causing the thin wall portion of the sealing gasket to rupture due to internal pressure, the abnormal gas pressure inside the battery is discharged to the outside of the battery, thereby preventing the battery from bursting during abnormal use. <Problems to be solved by the invention> However, for example, when a battery is used at high temperatures, the sealing gasket may soften and stretch, or when placed in a fire, the sealing gasket may melt. Therefore, in such cases, it is difficult to rupture the sealing gasket at a predetermined time when the internal force of the battery increases, and the abnormal gas pressure is incompletely discharged, making it difficult to provide effective explosion protection and leading to an explosion. Something happened. Especially if the battery is charged due to misuse,
This tendency is remarkable because the rate of increase in battery internal pressure is extremely fast. <Means for solving the problem> The cylindrical alkaline battery of this invention has two to
In a cylindrical alkaline battery in which a positive electrode terminal having four projection portions provided at approximately equal angular intervals on the circumference is integrated with the positive electrode can by resistance welding, at least in the welded portion, the plate of the positive electrode can The gist is that the thickness is 90% or less of the plate thickness of the positive electrode terminal. <Function> In a cylindrical alkaline battery in which the positive terminal is integrated with the positive electrode can by welding it to the bottom outer periphery of the positive electrode can, the internal pressure of the battery increases due to abnormal use of the battery, causing the bottom surface of the positive electrode can to swell. In this case, a force is applied to lift the positive terminal, and this force is applied to two to four points (preferably 3
The force is concentrated at the point), and this generates a force that tries to peel off the weld. At this time, as mentioned above, by making the thickness of the positive electrode can thinner than the thickness of the positive electrode terminal, making it less than 90% thick, the plate material at the bottom of the positive electrode can can be peeled off at the welding points at these several points. At the same time as the positive electrode terminal peels off, abnormal gas inside the battery is discharged to the outside of the battery through the peeled hole. <Example> An example of this invention will be described below using the accompanying drawings. In FIG. 1, on the bottom of a positive electrode can 1 housing a power generation element (not shown), a positive electrode terminal 2 is formed in a shape corresponding to the bottom surface of the positive electrode can and has a terminal for taking out current in the center. It is placed. That is, on the bottom surface of the positive electrode can 1, there is a flat part 1 on the outer peripheral side.
a, a bead portion 1b, and a central flat portion 1c are sequentially formed from the outer periphery. On the other hand, the positive electrode terminal 2 has a first flat part 2a that is in close contact with the outer peripheral flat part 1a, a bead part 2b that is fitted into the bead part 1b, and a part located on the central flat part 1c. 2 flat portions 2c and a central protruding terminal portion 2d for current extraction are formed in sequence. Further, in order to ensure welding, three projection portions are provided on the first flat portion 2a of the positive electrode terminal 2 at intervals of 120° on the circumference on the side facing the bottom surface of the positive electrode terminal.
This projection part has a diameter of approximately 0.5 mm and a height of approximately
It is 0.3mm and resistance welding is done at this point.
The projection section may have two or four points, but usually three points are provided for stability. Further, the thickness at the outer peripheral flat portion 1a of the bottom surface of the positive electrode can is about 0.3 mm, and the thickness at the first flat portion 2a of the positive electrode terminal 2 is about 0.4 mm. The dimensions of each part are 0.15mm or more for positive electrode can 1 due to its strength as a battery case, and for positive electrode terminal 2 due to parts processing.
Desirably 0.5mm or less. The material for both the positive electrode can 1 and the positive electrode terminal 2 was a nickel-plated steel plate having a Hv (Vickers hardness) of 100 to 130, which is commonly used. Then, connect the positive electrode can 1 and the positive terminal 2 to 3 in this way.
With the dot projection part in close contact,
As shown in Figure 2, spot resistance welding is carried out at three locations approximately equally spaced around the same circumference on the outer circumferential flat part 1a and the first flat part 2a (portions indicated by "X" in the figure). After the positive electrode can 1 and the positive electrode terminal 2 are integrated, a heat-shrinkable adhesive label for the exterior is attached to the outer periphery of this unit cell to obtain a completed battery. When the battery of this example is used abnormally, such as by charging, as shown in Figure 3, the bottom of the positive electrode can bulges upward in the figure due to the internal pressure of the battery, and the positive electrode terminal 2 It deforms upward in the figure, and as a result, a force is generated in the direction of peeling off the welded portion between the positive electrode terminal 2 and the positive electrode can 1. If the internal pressure of the battery increases further, as shown in Figure 4, the weld on the bottom side of the positive electrode can peels off, creating a hole in the bottom of the positive electrode can, and through this hole, the abnormal gas pressure inside the positive electrode can is released into the battery. released to the outside. Table 1 shows the degree of peeling at the weld of LR20, which was manufactured by changing the thickness of the positive electrode terminal 2 at the weld and the thickness of the bottom of the positive electrode can 1. In the experiment, the sealing part that normally operates as a safety valve was sealed, and the internal pressure of the battery was intentionally increased to 40 Kg/cm ² for observation. 40
If the pressure exceeds Kg/ ^cm2 , the battery seal will come off.
In other words, it would burst, so it makes no sense.

[Table] In Table 1, * indicates that, as shown in FIG. 5, the positive electrode terminal 2 was peeled off, but there was a hole in the welded part on the positive electrode terminal 2 side, and there was no hole in the bottom side of the positive electrode can 1. <Effects of the invention> As described above, according to the cylindrical alkaline battery of this invention, when the battery is used abnormally, the weld between the positive electrode can and the positive terminal is broken, and abnormal gas inside the battery is released from this broken part. Since the battery is discharged to the outside of the battery, it is possible to reliably prevent the battery from bursting even when the battery is used abnormally at high temperatures, thereby improving the safety of the battery.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the battery of the example before welding, Figure 2
The figure is a cross-sectional view after welding, Figure 3 is a cross-sectional view when the battery of the example is used abnormally, Figure 4 is a cross-sectional view showing the battery of the example with the bottom surface of the positive electrode case broken, and Figure 5 is a sectional view of the sample in Table 1 in which no gas was discharged. 1... Positive electrode can, 2... Positive electrode terminal.

Claims (1)

[Scope of Claim for Utility Model Registration] A positive electrode terminal having two to four protrusion portions arranged at approximately equal angular intervals on the circumference on the outer periphery of the bottom of a positive electrode can in which a power generation element is hermetically housed is connected to the positive electrode can. A cylindrical alkaline battery integrated by welding, wherein the thickness of the positive electrode can is 90% or less of the thickness of the positive terminal at least at the welded portion. .